Java tutorial
/* * Copyright 2011 SWM Services GmbH. * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. */ package de.swm.commons.mobile.client.widgets; import com.google.gwt.editor.client.IsEditor; import com.google.gwt.editor.client.adapters.TakesValueEditor; import com.google.gwt.event.dom.client.*; import com.google.gwt.event.logical.shared.HasValueChangeHandlers; import com.google.gwt.event.logical.shared.ValueChangeEvent; import com.google.gwt.event.logical.shared.ValueChangeHandler; import com.google.gwt.event.shared.HandlerRegistration; import com.google.gwt.text.shared.Renderer; import com.google.gwt.user.client.DOM; import com.google.gwt.user.client.Timer; import com.google.gwt.user.client.ui.*; import de.swm.commons.mobile.client.SWMMobile; import de.swm.commons.mobile.client.base.PanelBase; import de.swm.commons.mobile.client.widgets.itf.IProvidesKeyAndValue; import java.util.Collection; import java.util.HashMap; import java.util.Map; /** * Listbox that supports data binding and internationalization * * @param <T> the list box type */ public class DropDownList<T> extends PanelBase implements FocusHandler, BlurHandler, ChangeHandler, HasValueChangeHandlers<T>, IsEditor<TakesValueEditor<T>>, HasConstrainedValue<T>, HasFocusHandlers, HasBlurHandlers, HasEnabled { private final ListBox listBox = new ListBox(); private final Map<Integer, String> indexKeyMap = new HashMap<Integer, String>(); private final Map<String, Integer> keyIndexMap = new HashMap<String, Integer>(); private TakesValueEditor<T> editor; private IProvidesKeyAndValue<T> keyValueProvider; private Renderer<T> renderer; private int lastIndex = 0; private T currentValue; /** * Default constructor. */ public DropDownList() { super(); myFlowPanel.add(listBox); if (!(SWMMobile.getOsDetection().isIOs())) { myFlowPanel.add(new HTMLPanel("")); myFlowPanel.add(new HTMLPanel("")); myFlowPanel.add(new HTMLPanel("")); } setStyleName(SWMMobile.getTheme().getMGWTCssBundle().getDropDownCss().dropDownList()); listBox.addFocusHandler(this); listBox.addBlurHandler(this); listBox.addChangeHandler(this); } /** * Clears the drop down list. */ public void clear() { indexKeyMap.clear(); keyIndexMap.clear(); lastIndex = 0; listBox.clear(); } @Override protected void onUnload() { removeStyleName(SWMMobile.getTheme().getMGWTCssBundle().getDropDownCss().focus()); super.onUnload(); } @Override public void onFocus(FocusEvent event) { addStyleName(SWMMobile.getTheme().getMGWTCssBundle().getDropDownCss().focus()); } @Override public void onBlur(BlurEvent event) { removeStyleName(SWMMobile.getTheme().getMGWTCssBundle().getDropDownCss().focus()); } @Override public HandlerRegistration addBlurHandler(BlurHandler handler) { return listBox.addBlurHandler(handler); } public void clearSelection() { lastIndex = 0; new Timer() { @Override public void run() { listBox.setSelectedIndex(0); } }.schedule(100); } @Override public HandlerRegistration addFocusHandler(FocusHandler handler) { return listBox.addFocusHandler(handler); } @Override public void onChange(ChangeEvent event) { ValueChangeEvent.fire(this, getValue()); } /** * Sets the size of the Drop Down List */ public void setSize(String width, String height) { listBox.setSize(width, height); } /** * keyValueProvider the keyValueProvider to set. * * @param keyValueProvider the keyValueProvider to set */ public void setKeyValueProvider(IProvidesKeyAndValue<T> keyValueProvider) { this.keyValueProvider = keyValueProvider; } /** * renderer the renderer to set. * * @param renderer the renderer to set */ public void setRenderer(Renderer<T> renderer) { this.renderer = renderer; } @Override public void add(Widget w) { assert w instanceof DropDownItem : "Can only contain DropDownItem in DropDownList."; DropDownItem item = (DropDownItem) w; if (keyValueProvider != null) { // die idee ist, dass nur key's hinzgefuegt werden > das sind die auswahlbaren enum werte if (this.keyValueProvider.getValue(item.getKey()) != null) { T value = this.keyValueProvider.getValue(item.getKey()); this.keyIndexMap.put(item.getKey(), lastIndex); this.indexKeyMap.put(lastIndex, item.getKey()); listBox.addItem(this.renderer != null ? this.renderer.render(value) : String.valueOf(value), item.getKey()); lastIndex++; } } else { // support String as Type T (shortcut) listBox.addItem(item.getText(), item.getKey()); } } public ListBox getListBox() { return listBox; } /** * Returns a {@link TakesValueEditor} backed by the ValueListBox. * * @return the value */ public TakesValueEditor<T> asEditor() { if (editor == null) { editor = TakesValueEditor.of(this); } return editor; } @SuppressWarnings("unchecked") @Override public T getValue() { int index = listBox.getSelectedIndex(); if (index >= 0) { if (keyValueProvider != null) { return this.keyValueProvider.getValue(this.indexKeyMap.get(index)); } else { // support String as Type T (shortcut) return (T) listBox.getValue(index); } } return null; } @Override public void setValue(T value) { Integer indexToSelect = 0; if (keyValueProvider != null) { final String key = this.keyValueProvider.getKey(value); if (key != null) { indexToSelect = this.keyIndexMap.get(key); } } else { // support String as Type T (shortcut) String stringValue = (String) value; for (int i = 0; i < listBox.getItemCount(); i++) { if (listBox.getValue(i).equals(stringValue)) { indexToSelect = i; break; } } } listBox.setSelectedIndex(indexToSelect); this.currentValue = value; } @Override public void setValue(T value, boolean fireEvents) { final T oldValue = currentValue; setValue(value); if (fireEvents) { ValueChangeEvent.fireIfNotEqual(this, oldValue, value); } } /** * Will register a value change handler * * @param handler the handler to add. * @return the registration handle. */ public HandlerRegistration addValueChangeHandler(ValueChangeHandler<T> handler) { return this.addHandler(handler, ValueChangeEvent.getType()); } @Override public void setAcceptableValues(Collection<T> values) { // intentionally left empty } @Override public boolean isEnabled() { return !DOM.getElementPropertyBoolean(listBox.getElement(), "disabled"); } @Override public void setEnabled(boolean enabled) { DOM.setElementPropertyBoolean(listBox.getElement(), "disabled", !enabled); } }